It is simple. I keep a couple of spokes with rusted on nipples and the
elbows cut off, but that's not required.
Put a spoke in each of two diametrically opposite holes; thread a nipple
onto each until the spoke is flush with the end of the nipple, pull them
taut.
Measure the distance between the inside curve of the elbows at the
centre. Call this "A". If your spokes overlap then the value of A is
negative.
Measure the length of one spoke with a nipple threaded on flush as
before. Bottom of head of spoke nipple to inside of elbow. Call this "B".
ERD = A + 2*B
Repeat for <some small number> of opposite holes, just in case your rim
is slightly out-of-round. I hadn't thought of this. Good idea.
jtaylor said:"D'ohBoy" <[email hidden]> wrote in message
news:[email hidden]...
Quoted message said:JT said:Two spokes, two nipples, and a ruler will tell you the ERD.
JT:
Assume I am an idiot (perhaps not far off) and explain the methodology
for doing as you suggest.
No, but it is simple.
Put a spoke in each of two diametrically opposite holes; thread a nipple
onto each, pull them taught.
Measure the distance between the ends of the nipples closest to the centre.
Call this "A"
Measure one nipple. Call this "B"
ERD = A + 2*B
Repeat for <some small number> of opposite holes, just in case your rim is
slightly out-of-round.